1. Field of the Invention
The present invention relates to a method of printing registered images onto edible pieces, and particularly onto shaped edible pieces. The invention also relates to an apparatus for practicing the method of the invention and to edible pieces having a multicolor registered composite image on a planar or non-planar surface thereof.
2. Description of the Related Art
Many multicolor printing methods are known in the graphic arts which are capable of producing registered images on non-food products. These methods include relief printing, stamp-printing, offset printing, pad printing, flexographic printing, gravure printing, inkjet printing, and silk-screen printing. Application of such methods to multicolor registered printing on edible pieces, however, is difficultxe2x80x94particularly for printing onto non-planar surfaces. The handling of edible pieces entails different considerations from the handling of paper or polymer sheets, as edible pieces require more careful handling to prevent damage or misshaping of the pieces. Further, handling food generally requires higher cleanliness. As the inks must be edible, as well as the substrates, the artisan has a smaller universe of materials and methods from which to select to achieve the desired high resolution results. Due to these constraints, the high volume production of high resolution registered multicolor images on edible substrates is a difficult technical problem.
Methods for printing composite images onto large solid articles such as bottles and other storage cylinders using a single transfer roll are known. U.S. Pat. No. 4,519,310, for example, describes transferring a plurality of inks onto the outer periphery of a single ink form roller, pressing a cylindrical container against the ink form roller, and rotating the cylindrical container to transfer the ink images onto the cylindrical container. The method described in U.S. Pat. No. 4,519,310 however has not been adapted for printing edible inks onto shaped edible pieces.
Presently, at high speed mass production, designs applied to non-planar surfaces of edible pieces are generally limited to one-color designs (or multiple independent designs that can be of different colors, but are unrelated to each other) because it is very difficult to apply consecutive images in registry to non-planar surfaces of edible pieces.
Methods of forming composite or registered images on a confectionery are disclosed in copending U.S. application Ser. No. 09/479,549, herein incorporated by reference in its entirety. The apparatus and processes described therein are directed to a unique system of conveying the pieces in registration between printing stations. One component image of the registered image, typically a first color, is printed at a first print station and then a second image of a second color is printed in registration with the first image at a second print station to produce a complete registered image. Each print station is equipped with a separate transfer roll, as shown in FIG. 6 herein.
A drawback of such multiple-printing-station technology is the need for keeping the shaped edible pieces in registration between print stations. Vacuum systems, which may be used for this purpose, for example, consume excessive amounts of power and must be carefully maintained.
The present invention represents an advancement in the art in that it provides a method and apparatus for printing multicolor registered images on edible pieces without the necessity of means for maintaining the pieces in registering relationship between printing stations. The invention also provides a system of multicolor registered printing which can be readily retrofitted to existing confectionery printing technology.
Another advantage of the present invention is improved image registration compared to the existing technology. As good as the vacuum system is, there can still be some movement of the edible piece causing a degree of loss of registration. This problem is eliminated by printing the component images on a transfer roll where the system is not subject to movement.
The technology of the invention utilizes a single image transfer surface for printing a registered image on an edible piece. Instead of forming the components of the image on the edible piece at separate printing stations, a registered image is formed at different times on an image transfer surface. The entire registered image is then transferred onto the edible piece in one contact step.
Broadly, an apparatus for printing a multicolor registered image onto a surface of an edible piece according to the invention comprises a recess for holding an edible piece situated on a conveyer which moves the piece past an image transfer surface. The image transfer surface (which in preferred embodiments is the surface of a rotating cylinder) contacts the edible piece in the contact step which transfers the multicolored registered image onto the piece.
The apparatus requires at least first and second application surfaces for applying color medium to the image transfer surface, although three or more application surfaces may be used. The application surfaces are supplied with color media, such as food grade inks (white, black and other colors) by first and second edible color medium supplies.
First and second patterns of edible color medium (the component images) are applied by the application surfaces at different times onto the image transfer surface and then the registered image is transferred onto a surface of the edible piece in a single contact step.
This invention is also directed to an edible piece having a multicolored composite image formed from at least two component images of edible printing inks deposited on at least one non-planar surface of the edible shaped piece. Particularly preferred edible pieces include shaped confectionery pieces having lentil, oval, spherical, or the is like shaped confectionery, most preferably sugar shell coated confectionery such as for example, xe2x80x9cMandM""s(copyright)xe2x80x9d Chocolate Candies pieces, xe2x80x9cSKITTLES(copyright)xe2x80x9d Bite Size Candies and the like.